Conventionally, there are known in-vehicle devices that have a function serving as devices for connecting different networks (for example, see Patent Literature 1). With this technology, an in-vehicle device receives, from, for example, a mobile terminal, control information that includes therein both operation information that indicates the operation content that is used to control the in-vehicle device and information that specifies the mobile terminal. Then, the in-vehicle device determines whether the in-vehicle device accepts the operation specified by the operation information on the condition that the mobile terminal that has sent the control information is the mobile terminal that is allowed to perform a keyless entry and, if the in-vehicle device accepts the operation, the in-vehicle device performs a process in accordance with the operation information.
Patent Literature 1: Japanese Laid-open Patent Publication No. 2013-148435
However, with the conventional in-vehicle device, there is a problem in that, even if data sent from outside is malicious data, if the transmission source of the data is authorized, the in-vehicle device performs a process in accordance with the data. For example, in the conventional technology, if a mobile terminal that has sent the control information, in which both the operation information and the information that specifies the mobile terminal are included, is a mobile terminal that is allowed to perform a keyless entry, the in-vehicle device performs, in accordance with the operation information, the function that is allowed to perform the operation specified by the operation information. Accordingly, even if the operation information is malicious information, if the operation information is from the mobile terminal that is the transmission source is authorized, the in-vehicle device performs the function that is permitted to perform the operation specified by the operation information.